1. Field of the Invention
The present invention relates to a facsimile apparatus that can utilize a double-side communication protocol conforming, for example, to ITU-T Recommendation T.30 to perform facsimile communication.
2. Description of the Related Art
Two modes are defined in the double-side communication protocol conforming to ITU-T Recommendation T.30. They are alternate mode and continuous mode.
In the alternate mode, an image on the obverse side of each original sheet and an image on the reverse side thereof are alternately transmitted. In the continuous mode, the image on the obverse side of the original sheet is first continuously transmitted, and the image on the reverse side thereof is then continuously transmitted.
In either mode, consecutive page numbers are sequentially assigned to respective images. More precisely, page number 1 is assigned to the image on the obverse side of first sheet; page number 2 to the image on the reverse side of the first sheet; page number 3 to the image on the observes side of the second sheet; page number 4 to the image on the reverse side of the second sheet; and so forth. The page number is transmitted in the form of a PPS message (communication procedure), immediately after the image data, from the transmission side to the reception side. Furthermore, it is also notified to the reception side from the transmission side via the PPS message that each image belongs to the obverse side or reverse side of the original sheet.
In the reception side, two images identical to those read from the obverse and reverse sides of each original sheet in the transmission side can be printed on the obverse and reverse sides of a sheet, in accordance with the PPS messages that show the page number and which image is printed on which side obverse side.
Additionally, the facsimile apparatus can automatically add and transmit the image of a cover sheet which is stored in a memory as first-page image.
When the cover-sheet adding function is utilized in transmitting the images on both side of each original sheet, the images of the original sheets, actually read, are transmitted as the second page et seq. The respective images are sequentially numbered, and the first image is numbered as “page 3.”
Since only a top one page of the image on the obverse side is added as the cover sheet, however, the image of the reverse side of the first page (page number “2”) is not transmitted.
Assume that the page numbers of the incoming images are checked. Any page missing is detected as a communication error in the reception side. In this case, the cover sheet may be added and the image having page number “2” may not be transmitted as described above. This will be detected as a communication trouble.
To solve the problem, no check may be made for any possible page missing. In this case, however, even the page missing due to a communication trouble cannot be detected, remarkably deteriorating the reliability of communication.
Moreover, when double-side image transmission is performed, the images on both sides of any original sheet are regarded as objects to be transmitted.
Therefore, even the reverse side of the cover sheet is scanned and the image on this side is transmitted when the cover-sheet adding function is not used and the user prepares the cover sheet and adds it to the original sheet before the images of the original sheet is transmitted.
Generally, information is formed on only one side of the cover sheet. In many cases, the cover sheet is not be used again after the image on the original sheet has been transmitted. Therefore, a sheet already used the reverse side is used as the cover sheet, and the information of the cover sheet is formed on the obverse side. Even the image on the reverse side, which should not be transmitted, is inevitably transmitted during the double-side image transmission.